Control valves for hydraulic presses



July 3, 1956 J. M. TOWLER ET AL 2,752,946

CONTROL VALVES FOR HYDRAULIC PRESSES Filed Aug. 1e, 1951 2 sheets-sheet 1 22 29 six-m., 29

21 8a 2/ 2O 5'* 3o 1 y 'l 3/ Y 2e Inventors John maurice Towler Frank HathornTowler f3? MAW WWW/4f Attorneys July 3, 1956 J. M. TOWLER ET AL CONTROL VALVES FOR Filed Aug. 18, 1951 HYDRAULIC PRESSES 2 Sheets-Sheet 2 /nvenf'ors John maurice Ruder' F' rank Ha thorn 7nwler /gf n@ @www3 Afro/n eyS 2,752,946 Patented July 3, 1956 CONTROL VALVES FOR HYDRAULIC PRESSES John Maurice Towler, Rodley, near Leeds, and Frank Hathorn Towler, Doh Park, nearOtley, England; Frank H. rliowvler, administrator of said .lohn M. Towler, deceased, assiguors to Electraulic Presses Limited, Rodley, near Leeds, England, a British company Application August 18, 1951, Serial No. 242,546 Claims priority, application Great Britain August 26, 1950 S Claims. (Cl. 137-622) rthis invention relates to control valves for hydraulic presses of the direct-hydraulic type in which pressure liquid to actuate the press is supplied directly by pumps. in particular this invention relates to upwardly acting hydraulic presses in which the pressing stroke is in an upward direction.

One object of this invention is to provide an improved construction whereby the control valve is mounted upon a combined preiilling and exhaust valve and is adapted to actuate the said exhaust valve to effect the return stroke of the press ram, the said combined valve being equally sutiable for employment with a hydraulic press having one press ram or having a multiplicity of press rams.

Broadly the present invention consists of a combined control prelling and exhaust valve for use with an hy- 1 n n drauhc press and in combination with an automatic atmission valve wherein with the control valve in the neutral position both the pump and the approach cylinders of the press are free to exhaust by way of the control valve, with the control valve in the return stroke position the exhaust valve opens to permit the one or more press rams to exhaust concurrently with the pump and the approach cylinders which are still free to exhaust through the control valve and with the control Valve in the pressing position the exhaust valve is free to close and delivery from the pump is diverted to the approach cylinders until a pressure rise in such cylinders effects operation of the automatic admission valve when the pump is permitted to deliver to the one or more press cylinders as well as the approach cylinders.

One embodiment of this invention consists of a manually operated single acting control valve mounted upon a combined pretilling and exhaust valve, the axis of the control valve spindle being co-axial with the axis of the said combined valve, the spindle of the control valve being connected to the combined valve in such a way that, when it is moved to the return position, it actuates the exhaust valve causing the said valve to open so as to permit pressure liquid from the press cylinder to pass back to the pump supply tank and so arranged that, when the control valve spindle is moved in the opposite direction, towards the pressing position, the said exhaust valve is permitted to close. The combined prelling and exhaust valve comprises three mushroom type valves mounted concentrically one within the other. The largest mushroom type valve functions as a prelling `valve and is seated in the main valve casing on which the control valve is mounted with the axis of the valve spindle co-axial with the axis of the prelling valve. The prelling valve is held closed by a spring or springs acting in opposition to the pressure of liquid from the `supply tank which tends to open the valve. The exhaust valve is seated within the prelling valve head and is held closed by a spring. The exhaust valve head is enlarged to form a piston which is enclosed by a cylindrical bore Within the pretilling valve head and it is so arranged that the exhaust valve head functions as a piston within the bore in the prelilling valve head which functions as the associated cylinder.

The annular area of the piston surrounding the exhaust valve seat is subject to the pressure within the press cylinder; the full area of the piston within its associated cylinder is also subject to the pressure within the press cylinder by means of a very small communicating passage, but it may be placed in free communication with the supply tank by opening a small mushroom type valve which is seated in the pistn of the exhaust valve head. An actuating spindle passes down the centre of the exhaust valve stem and it is so arranged in association with the control valve that it lifts the small mushroom type valve ofi its seat when the control valve spindle is moved to the return position, and it permits the small mushroom valve to close when the control valve spindle is moved to the neutral position.

ln order that the invention may be clearly understood and carried into effect two embodiments of the same will.` now be described by aid of the accompanying drawings in which Fig. l is a somewhat diagrammatic view in section of the complete valve according to one embodiment and Fig. 2 is a view of a detail to an enlarged scale showing a further embodiment in which the automatic opera-- tion of the exhaust valve according to the lirst embodi` ment is supplanted by mechanical operation.

The valve illustrated in the drawings is for the purpose of controlling the return stroke of the one or .more rams of an upwardly acting hydraulic press and for this purpose it is used in conjunction with an automatic admission valve and a spring loaded decompression or relief valve, neither or which valves are illustrated ni the drawings.

The valve of the present invention, according to one ernbodiment illustrated, has in combination a control valve, a prefilling valve, and an exhaust valve.

Referring to the drawing, the control valve consists: of a plunger 1 working in a cylinder 2 within which it is reciprocable by operation of a hand lever The valve plunger l has two full diameter portions separated by a portion i of reduced diameter and within the cylinder 2 are cut two annular grooves 5 and o that are separated, by an annular ring '7 having an integral diameter nearly the same as the full external diameter of the plunger sothat one is a working fit within the other.

The annular groove 5 receives pressure liquid from ai pump or accumulator through a connection ti, said pump' also being connected to the approach cylinders of the press.

The main casing of the combined valve of the present, embodiment consists of two pipe sections 9 and itl which are bolted together so as to grip between them an annular member 11 forming on one side a seat for the prefllliug valve and having on the opposite side a spider for supporting a guide bush for the spindle of the exhaust valve.

The cylinder 2 of the control valve plunger l is mounted on a hollow support l2 branching from the pipe section 9 which is curved and terminates in a 'lange t3 for connecting the section to a pump reservoir or preill tank not shown. The opposite end of the other pipe section liti terminates in a llange ld, but in this case such flange is for connecting this pipe section to the one or more press cylinders. also not shown. p

As it is desired that liquid trom the pump or accummulator entering through the connection t; shalt be free to flow into the upper pipe section 9 in two positions of the operating lever It, the annular groove t5 rendered permanently open to the interior of said pipe section 9 by means of a series of holes or channeis Liquid entering into annuiar groove is free to pass to the other annular groove d, and so into the pipe section 9, by reason of the reducedportion 4 of the control valve plunger l bridging, in these two positions of the operating lever, the two annular grooves S and 6.

By pulling the lever 3 to the left in the drawing, the

control valve plunger l is pulled upwards thus moving the lower full diameter portio-n into the section of the cylinder bore constituted by the annular ring 7. The annular groove is thus isolated from the annular groove 6 and in consequence the 'pressure liquid from the pump or accumulator is forced to How' to the approach rams of the hydraulic press and, upon actuation of the automatic admission valve, also "to the one or more main rams of the press through an opening 8a in the lower pipe section 10.

The preilling and exhaust valves according to the construction illustrated are in axial alignment with the control valve and consist, in the case of the prelling valve, of a valve member 16 ywhich is supported by a spring 17 acting on a plunger i8, with the upper chamfered edge of the member in engagement with a seating i9 on the underside of the annular member li, and in the case of the exhaust Valve, of a pistorrlihe member Ztl working in a cylinder 21 within the` interior of the prefilling valve member i6.

The upper edge of the exhaust valve member 2li is chamfered and seats against a seating constituting the chamtered lower edge of an open-ing 22 communicating with the interior of the upper pipe section 9. With the exhaust valve member 20 in the open position liquid from the press is permitted to pass-from the lower pipe section to the upper pipe section 9 by way of radial passages 23 in the prellvalve member 16 and opening 22.

The exhaust valve member 2t) is held in the raised or closed' position by a spring 24 acting' against an enlarged head 25 on the upper end of a stem 26 attached to or forming an integral part of the exhaust valve member.

With the exhaust valve in the closed position there is provided' beneath the member Z0 a space 27 which is in open communication with the interior of the lower pipe section it) by way of a small hole 28. By suitably reducing the upper end of the exhaust valve member there is' provided an annular surface' 29 against which the pressure liquid from the interior of thek lower pipe section, entering through the passages 23, can act in opposition to the pressure within the space 27. Both ends of the exhaust valve member, therefore, are under the influence of the pressure in the press cylinder and normally the member is held closed against its seating by the spring 242- and the superior pressure on its lower end.

To destroy this balance and permit the exhaust valve to be forced away from its seating it is necessary that means be provided whereby the space 27 is opened to exhaust. In the example illustrated such means takes `the form. of a small mushroom valve 30 which is held against itsA seat by a spring 31 and is adapted to be forced oi its seat by the plunger l of the control valve iny its downward movement through the intermediary of a spindle 32 forming an extension of the plunger l to which it is connected by adjusting means 33 which permit thereffective length of the spindle 32 in relation to the valve 30 to be suitably Varied.

The valve 30 has a stern 34 vwhich is a sliding fit in a bore in the body of the exhaust valve Ztl and this bore forms a continuation of a bore extending up the stem 26 of the exhaust valve in which tits slidably, the lower end of the spindle 32.

The stem 34 of the valve 3% hasl an axial passage 35 at its centre which is closed at the valve head end and open at its upper end. This upper end is reduced in diameter andthe thin wall thus formed is pierced by radial slots 36. Similarly radial holes 37 pierce the wall of the stem at its lower end just above the head of the valve 30 and these latter holes form a communication between the lower end of the axial passage 35 and a circumferential groove 3S formed by suitably reducing the diameter of the surrounding portion of the stem 34.

When the valve 30 is forced downwards oit its seat the groove 3S" is' rendered'open to the Space 27 beneath the exhaust valve Z. Liquid within this space is thus permitted to ow into the axialpassage 35 and'out through the radial slots 36. As the upper open end of the passage 35 is closed by the contacting end of the spindle 32, lateral passages 39 are provided in the wall of the stem 26 through which the liquid flowing from the space 27 can escape' into the interior vof the upper pipe section 9.

The above construction is best seen upon reference to Fig. 2 illustrating an embodiment in which the exhaust valve member 20 `isvof vlthe same diameter throughout its length.

Now let us consider the employment of a control valve such as described above for operating an upwardly acting hydraulic press having a press ram and two approach rams and actuated .by pressure liquid supplied by a hydraulic pump. The manually operated control valve is so arranged and connected that when the control valve spindle is in the neutral and return positions the liquid from the pump and from the approach cylinders is freely bypassed bacl'i' to the pump supply tank; and, when the control valve spindle is inthe pressing position, raisedv position1 in Fig'. l, thep'ressure liquid from the pump is directed to the approach cylinders. Thus, when the control valve spindle is movedI upwardly tov the pressing4 position the approach rams lift the press table and associated 'press ram yup tothe work and during this approach stroke the press cylinder is so connected that it is filled with liquid from' the pump supply tank passing through the prell valve which' is opened against the spring 18 by the dilerence of lpressure or head of liquid. When the press table meets the work the automatic admission valve, actuated by the pressure in the approach cylinders, directs pressure liquidv from' the pump through passage 82L to the press cylinder in addition to the approach cylinders; the prelling valve is closed as the pressure builds up yin the press' cylinder, and therefore in pipe section 10, and the pressing opera tiony is performed. When the control valve spindle is moved to the neutral position shown in' Fig'. 1, liquid from the approach cylinders is bypassed through the control valve by way ofpassage 8 to exhaustV and the pump is bypassed; liquid is locke'd in the press" cylinder by the preiilling valve whichis closed, but pressure in the press cylinder is allowed to fall gradually'by the aforesaid spring loaded deco'mpression valve, or throttling` valve which is interposedl between'the presscylinder and the pipe line, between the approach cylinders and the control valves, which is now connected'to exhaust.` The said decompressionv valve is so arrangedlthatthe ow is in one direction only, away from-the press` cylinder, .and so adjusted that the pressure falls to a figure `such that it is just suicient to support the weight .of the press table and moving parts. This" decompression valve may be described very briefly as a relief valve which is so constructed that the spring load and the valve lift or opening are independently adjustable; the sprinygfloady being adjusted so-that the ultimate pressure'at: which the valve closes is suthcient to support the weight of the moving parts; and as the valve` lift or opening .determines the rate of decompression, the latter is adjusted' to give the desired rate. When the control valvespindle is moved downwardly to the return position, the small mushroom valve 30 is actuated bythe control valve spindle so as to place the space 27 beneath lthe piston of the exhaust valve in communication with the supplytank and this permits the exhaust valvetobe opened' bythe pres sure in the press cylinder actingon the annulus' 29 of the exhaust valve piston. Withtheexhaustl valve open, the press cylinder is now in communicationl with the supply tank andthe press table is free to'faIl'byA gravity,-

liquid from the press cylinder' passingA through the exhaus't valve 20, and'liquid fromitlie approach cylinders passing through the control valve by w'ay o'f pass`age'8` to exhaust.

The embodiment illustrated in Fig..2 differs in function from that illustrated in Fig. 1 in that the orifice conrvr.

trolled by the small valve 36 is made very large in comparison with the hole 28 so that when the valve 30 is opened the space 27 will be n holly exhausted thus allowing the exhaust valve 20 to be pushed from its closed position to the open position by contact between the adjusting means 33 and the upper enlarged end of the stern 26 of the exhaust valve.

In the above embodiments the control valve is described as being manually operated; nevertheless the control valve may be remotely controlled or pilot-operated without departing from this invention. It will be further understood that the combined preiilling and exhaust valve may be mounted on a common manifold to supply a number of press cylinders having associated press rams which act in unison in association with a common press table. Furthermore, if increased pumping capacity is required, more than one pump may be employed.

We claim:

1. A combined control, pretll, and exhaust valve for hydraulic presses comprising, in combination, a hollow casing having a pressure uid inlet at one end and a pressure iluid outlet at the other end, a control valve supported on said casing having connections with a source of pressure fluid and with the inlet end of the casing, said control valve having a shiftable member operative in one position to block Huid flow from said source and in another position to direct fluid flow into said casing, a prefill valve member mounted within said casing so as to control communication between the two ends thereof and having opposite ends respectively subjected to the pressure of the fluid in the inlet and outlet ends of the casing, yieldable loading means normally operative to hold said valve member in a closed position in which it is effective to interrupt communication between the ends of the casing, said loading means permitting said valve member to move to an open position under the inuence of the pressure in the inlet end of the casing upon a predetermined decrease in the pressure in the outlet end of the casing, a passage in said Valve member aording communication between the ends c-f the casing when said valve member is in closed position, an exhaust valve normally positioned to close said passage, and means interposed between the shiftable member of said control valve and said exhaust valve for moving the latter to open position upon a shift of the control valve member to said other position.

2. A combined control, prell and exhaust valve as defined in claim l, in which said exhaust valve is in the form of a piston having differential areas' exposed respectively to the pressure in the inlet and outlet ends of the valve casing when the prell valve member is in closed position, and a relief valve operable to reduce the pressure on one end of the piston to permit its movement to open position by the pressure exerted on its other end.

3. A combined control, prell and exhaust valve as dened in claim 1, in which said exhaust valve is in the form of a piston having opposite ends exposed respectively to the pressure within the inlet and outlet ends of the casing, and a relief valve connected so as to reduce the differential between the pressures on the ends of the piston when opened and thereby condition said exhaust valve for movement to open position mechanically as an incident to the actuation of the control valve.

4. A control valve for hydraulic presses comprising, in combination, a hollow casing having a pressure fluid i11- let at one end and a pressure fluid outlet at the other end, a co-ntrol valve having connections with a source of pressure iiuid and with the inlet end of the casing, said control valve having a shiftable member operative in one position to block uid ilow from said source and in another position to direct fluid ow into said casing, a preill valve member seated within said casing so positioned that the upper area of said preiill valve member is exposed to the pressure in the inlet end of the casing and the lower area of the valve member is exposed to the pressure in the outlet end of the casing, yieldable means loading said prei'lll valve member into closed position with such force as to be overcome by a predetermined reduction in the pressure ditfercntial between the ends of the casing allowing fluid from the inlet end to bypass said prefrll valve member and flow through said outlet, and exhaust valve positioned within said pretill valve member, a passage connecting the outlet end portion of said casing to the inlet end portion of said casing which is closed by moving said exhaust valve, a spindle 'forming an extension of the control valve member engageable with said exhaust valve for positively opening the exhaust valve in response to a predetermined movement of the control valve member thereby allowing uid to exhaust from the outlet end of the casing through the inlet thereof.

5. A control valve for hydraulic presses comprising, in combination, a hollow casing having a pressure fluid inlet at one end and a pressure Huid outlet at the other end, a control valve having connections with a source of pressure huid and with the inlet end of the casing, said control valve having a shiftable member operative in one position to block liuid iiow from said source and in another position to direct fluid flow into said casing, a prell valve member seated within said casing and normally interrupting uid iiow between the inlet and outlet of the casing, yieldable means urging said preiill valve member into seated relationship with said casing, an exhaust valve slideable within saitl preiill valve member, a chamber above said exhaust valve, a portion of the base of which is an area or the top of said exhaust valve, an exhaust passageway interrupted by said exhaust valve, a relief valve within said exhaust valve, a relief passage* way associated with said relief valve, and means operable by said control valve member to shift said relief valve thereby allowing luid to flow from the outlet end of the casing through the relief passageway into said exhaust valve chamber, thereby reducing the differential pressure on said exhaust valve to facilitate its opening against the yieldable means which normally retains it in its seated position.

References Cited in the tile of this patent UNITED STATES PATENTS 616,197 Moller Dec. 20, 1898 1,143,236 Slater June 15, 1915 2,077,894 Patrick Apr. 20, 1937 2,210,284 Dinzl Aug. 6, 194() 2,345,360 Smith Mar. 28, 1944 2,406,727 Wetherbee Aug. 27, 1946 

